It is possible, on the basis of electrical potentials to draw conclusions about the brain activity of a human being. In particular, it is possible, in the case of a person who is asleep, to determine the individual sleep states, on the basis of the brain activity which is ascertained during sleep.
German patent application DE 1 99 20 433.0 to the present applicants describes a CPAP device system in which the characteristic of the respiration gas feed is varied in dependence on the sleep state of the patient. For that purpose, the required electrodes are glued onto the forehead of the patient by way of an adhesive-strip.
The correct application of such electrodes requires particular care and is frequently found to be unpleasant by the patient in question.